The Cub Den

The Cub Den

I have been using the following on a Sig 1/4 Scale cub from 2005. I have not had any issues with the setup.  All my scale plans I sell have this built into them.  I have also modified it to fit the Balsa USA and SIG Cub.  Please check out the plans at The Cub Den Store.   Please read through this article before starting the build. This setup can be added to a new or framed up Cub.  As with everything from The Cub Den, use at your own risk.  The Cub Den will not be held liable.

 Wing prep.

Build the wing per the manufacture plans except the following. Hinge filler blocks will need to be added between the back two spars in three locations refer to the drawing. I recommend installing all sheeting and cap strips to the bottom of the wing before you continue. Leave the top off for until the end.

Make the hinges.

You will need for each hinge a Dubro # 303 4-40 steel solder rod ends, 7/32 OD by 3.5 inches brass tubing, and 3/16 x 3/8 brass tubing. Drill a 1/8 hole through the rod end where the hinge pin will go. Insert a 1/8 OD brass tube through this hole and solder in place, do not allow solder to get inside the center of the tube. This tube must have an inside diameter of .1 inches.  Next solder the hinges up by putting the 3/16 on to the rod end followed by the 7/32 tub. Take a Dremel with a grinding or cutoff wheel attached to clean up any extra solder. I also like to roughen up the bras tubing so that the epoxy will adhere to them better. Make 6 of them.

Next drill the wing for the hinged. As you can see between the clams, I glued a square of hard balsa between the spars.  I made a small jig that I could clamp on to the wing to drill the hole. The jig is just some scrap hard wood that has an L cut into it so it will fit up flush with the back and bottom of the spar. I used a section of 7/32 ID tubing for the drill guide and glued it to the jig.  This could take some time to get the jig aliened to drill the holes. Drill all six holes using a 7/32 drill bit.

Now to make the other part of the hinge on the aileron.  I used some butterfly nuts or toggle nuts. Cut the center section out so the two halves will come apart.  Take the small half and drill hole through the holes using #36 or 7/64 bit. Next drill two small 1/16 holes in the back of the nut as in the photo.  Again, I recommend make a jig so you can drill all of them the same.  I use two small wood screws to attach the hinge to the aileron.



When I first setup my cub the nuts were easy to find with the holes on both parts. Now most of what I find has a hole with a slit on one side. I highly recommend staying away from them.

Hinge pins. Pick up a box of steel 6D nails. I picked this box up at Lowes. As you can see, they have a diameter of just a hair less than .1 inches.

The nails will need a little work before we can use them. I like to chuck them up in my drill press to do the work. The head of the nail will need to be ground down along with a little cleanup of the nail body. I grind the head down till about 1/32 is left around the nail. The way nails are stamped, sometimes it will leave two small webbings on each side of the nail close to the head. They will need to be ground smooth. Now take a measurement on how wide the hinges are to decide how long the pins need to be. You will need to make a small hole for a cotter pin.  I used a #64 bit for this hole.  Grind a small flat spot and take your time drilling the hole. Take a section of .02 brass wire and make cotter pins.

Making the ailerons

Ok let’s set the entire hinge making stuff to the side and build the aileron.

I like to cut ribs as a package. I start but cutting squares a little larger than the rib and then stake them so I can cut all sheets at one time. Use a couple long straight pins to keep the stack tighter during the cutting. Check and double check that your saw is cutting a true 90 deg to the table. You will need 13 blanks of 3/32 balsa for each wing. So, you should have two stacks of 13 blanks for the ailerons, one stack for each side. Cut the aileron ribs out for both wings and sand them smooth.

Let’s build the hinge ribs. Using 3/8 wide bass wood for the block. This will give you a 3/8 gap between the two ribs for your hinge. Glue at the angle per plans. You will need to make six of them. Don’t forget to go back and cut the 3/16 square grove in the top for the stringer.

You can see the layout of the ribs for the aileron. Using a 1/4 square balsa for the leading edge, 3/32 balsa for the trialing edge. Just your standard build, nothing special.

Next photo shows al the ribs in place and the 1/8 square balsa top spar in place. Next, I will take a razor plane and taper the trailing edge. Going from the tip of the rib to the back of the aileron, taper the trailing edge balsa so the top sheeting section of 3/32 will lie on top of it.


This is what it should look like

Next take a strip of 3/32 balsa and bind it as below. I used a section of round pipe, soaked the balsa down with water, place the balsa against the pipe and wrap with tape. Let dry overnight and it will give you a nice curve.

Now glue the top front sheeting of the aileron on.  Sand and shape the bottom leading edge of the aileron also. Next add the cat strips and fillers to the aileron and sand. Cut the openings for the aileron hinges as referenced on the plans.

Installing the hinge in the aileron is simple. I take a couple scraps of 1/32 balsa or brass and use them as shims. 

Place a pin through the hinge made from the toggle nut.  Insert hinge into opening and let the pin rest on the shims. Center the hinge in the opening and drill pilot holes into the hinge block and insert two small wood screws. Repeat for all six hinges.


Now a key point in the build of the ailerons.

Install the long sections of hinge that you soldered up in the begging and insert the pin in the hinge. Insert the hinges through the holes you drilled above in the wing. Using 5/32 this balsa, make a few shims that can be inserted between the back spar of the wing and the aileron. This will give you the clearance you will need for proper movement.

Keep the following in mind when gluing the bras hinge tubs to the wing. The bottom of the aileron must be flush with the bottom of the wing.  The shims must be between the wing and the aileron, and finally all three hinge points must be in a line. Take your time and get it all setup before you apply any epoxy.

So, we have our aileron setup now and all movement is smooth. Pull your hinge pins and separate the ailerons from the wing.  Make the short filler ribs for the aileron bay and glue them behind the wing ribs. Install top sheeting and cap strips to finish the wing.  Take a section of 1/32 balsa and fill in the curve part of the aileron bay.

Enjoy the setup. I have used this for several years on my Sig and scratch build L-4. I find that due to the fact of this being a scale aileron and works like a scale aileron that not as much ruder and will be needed to be coupled with the ailerons.

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